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Electric charge is a conserved property: the net charge of an isolated system, the quantity of positive charge minus the amount of negative charge, cannot change. Electric charge is carried by subatomic particles. In ordinary matter, negative charge is carried by electrons, and positive charge is carried by the protons in the nuclei of atoms ...
Static electricity is an imbalance of electric charges within or on the surface of a material. The charge remains until it can move away by an electric current or electrical discharge. The word "static" is used to differentiate it from current electricity, where an electric charge flows through an electrical conductor. [1]
The electric field was formally defined as the force exerted per unit charge, but the concept of potential allows for a more useful and equivalent definition: the electric field is the local gradient of the electric potential. Usually expressed in volts per metre, the vector direction of the field is the line of greatest slope of potential, and ...
The electrons, the charge carriers in an electrical circuit, flow in the direction opposite that of the conventional electric current. The symbol for a battery in a circuit diagram The conventional direction of current, also known as conventional current , [ 10 ] [ 11 ] is arbitrarily defined as the direction in which positive charges flow.
When an action potential occurs in a cell, the electrical signal reaches the presynaptic terminal and the depolarization causes calcium channels to open, releasing calcium to travel down its electrochemical gradient. This influx of calcium subsequently is what causes the neurotransmitter vesicles to fuse with the presynaptic membrane. [16]
If the electric field is strong enough, the free electron gains sufficient energy to liberate a further electron when it next collides with another molecule. The two free electrons then travel towards the anode and gain sufficient energy from the electric field to cause impact ionization when the next collisions occur; and so on.
where = is the distance of each charge from the test charge, which situated at the point , and () is the electric potential that would be at if the test charge were not present. If only two charges are present, the potential energy is Q 1 Q 2 / ( 4 π ε 0 r ) {\displaystyle Q_{1}Q_{2}/(4\pi \varepsilon _{0}r)} .
The term on the left is the rate of change of the charge density ρ at a point. The term on the right is the divergence of the current density J at the same point. The equation equates these two factors, which says that the only way for the charge density at a point to change is for a current of charge to flow into or out of the point.
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